Architecture in XP

[Peter Pascale]

Question for anyone who's seen or practiced XP, and hopefully Martin:
How is high-level architecture handled in the XP process? Does it receive the same treatment as design, in that it's done in tight iterations with significant refactoring? And how does that work on projects that involve a significant amount of enterprise architecture definition?
An example: Let's say I am embarking on a project to replace a legacy production management system for a light manufacturing company. The project has a unique opportunity to make a fresh start, Platform choice and DB choice are even open for consideration. Now, let's say the new system has to support web-enabled ordering, and production status, and reporting. And the manufacturer has 4 nationally distributed plants they want to eventually serve with the application. Not a high degree of integration across plants at first, just to be able to pass a job specification from one plant to the next. So now we have a distributed application, probably a need for messaging to preserve transactional integrity, perhaps a desire to incorporate some business logic components or a rules engine, and have to expose some functionality to web-based clients.
My only exposure to how such an architecture is created is to initiate an architectural specification process alongside the last 50% of the requirements process. How would such arch. issues be addressed in XP?
Thanks!
Peter

[martin fowler]

I would inclined to a little up front design here. Bear the following in mind.
Err on the side of simplicity.
Build little prototypes to see how things work in practice
Expect your architecture to evolve as the system evolves
Don't put in complex mechanisms that you aren't going to use in the early iterations. If you need them add them later